title: Effects of risperidone and olanzapine dose reduction on cognitive function in stable patients with schizophrenia: an open-label, randomized, controlled, pilot study.
abstract: Impact of dose reduction of atypical antipsychotics on cognitive function has not been investigated in stable patients with schizophrenia. In this open-label, 28-week, randomized controlled trial, stable patients with schizophrenia treated with risperidone or olanzapine were randomly assigned to the reduction group (dose reduced by 50% in 4 weeks and then maintained) or maintenance group (dose kept constant). Assessments at baseline and week 28 included the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Positive and Negative Syndrome Scale (PANSS), and Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). Sixty-one patients were enrolled; 2 of 31 (6.5%) and 5 of 30 (16.7%) patients prematurely withdrew from the study in the reduction and maintenance groups, respectively. While no significant differences in change in the PANSS total score were observed between the 2 groups, the reduction group showed significantly greater improvements in the RBANS and DIEPSS total scores compared with the maintenance group (mean ± SD, +7.0±7.1 vs -0.1±8.0, P < .001; -0.9±1.7 vs +0.1±1.2, P = .010, respectively). This 6-month pilot study suggests that risperidone or olanzapine dose reduction of 50% can improve cognitive function for stable patients with schizophrenia. Due to the open-label design, small sample size, and short study duration, however, there is a need to confirm the finding through double-blind, larger scale trials with longer follow-up periods. Moreover, potential risks of relapse following antipsychotic dose reduction should be thoroughly investigated in longer term studies.
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada. hirotak@dk9.so-net.ne.jp
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Takefumi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Gary
authors.initials: G
authors.lastname: Remington
authors.forename: Robert R
authors.initials: RR
authors.lastname: Bies
authors.forename: Takayuki
authors.initials: T
authors.lastname: Abe
authors.forename: Ariel
authors.initials: A
authors.lastname: Graff-Guerrero
authors.forename: Koichiro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Masaru
authors.initials: M
authors.lastname: Mimura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uchida
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000494:pharmacology; D001569:Benzodiazepines / Q000008:administration & dosage / Q000494:pharmacology; D003072:Cognition Disorders / Q000188:drug therapy* / Q000209:etiology; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D060046:Maintenance Chemotherapy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D000077152:Olanzapine; D010865:Pilot Projects; D011569:Psychiatric Status Rating Scales; D018967:Risperidone / Q000008:administration & dosage / Q000494:pharmacology; D012559:Schizophrenia / Q000150:complications / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D018967:Risperidone; D000077152:Olanzapine
keywords: antipsychotics; cognitive function; dose  reduction; olanzapine; risperidone; schizophrenia